This invention relates to headlamp assemblies and more particularly to an improved headlamp seal.
Automotive headlamps until the late 1930's consisted of a metallic reflector, a replaceable bulb, a glass lens, and some manner of bezel or molding to hold the lens in a position closing the open front end of the reflector. These units were replaced in about the 1939 and 1940 model vehicles by the well known sealed beam units in which the reflector and lens are formed of a single unitary glass structure and the bulb is encapsulated within the structure and is not replaceable. The sealed beam headlamps were legally mandated in the early 1940's by some governmental agencies.
Recently, however, due to pressures from automotive stylists, the mandate has been withdrawn and the stylists are now free to design the many exotic shapes of headlamps that are seen on modern day automobiles. The most typical construction for the new headlamps comprises a metal reflector, a bulb, a plastic lens, and a tongue and groove joint between the lens and the reflector augmented by some manner of adhesive. Problems have developed with this construction and, specifically, as the headlamp is turned on and off repeatedly the trapped air within the lamp heats and cools with a resultant increase and decrease in pressure and this increase and decrease in pressure fatigues the seal between the lens and the reflector, causes the seal to deteriorate, and eventually allows the leakage of moisture into the interior the lamp where it attacks the reflective surface of the reflector and forms beads on the interior surface of the lens which have the effect of scattering the light emitted by the headlamp and interfering with the delicate optical balance that had initially been designed into the lamp.